Commit
46e12c07b3b9603c60fc1d421ff18618241cb081 (MIPS: O32 / 32-bit:
Always copy 4 stack arguments.) change the O32 syscall handler to always
load four arguments from the userspace stack even for syscalls that
require fewer or no arguments to be copied. This removes a large table
from kernel space and need to maintain it. It appeared that it was ok
the implementation chosen requires 16 bytes of readable stack space
above the user stack pointer.
Turned out a few threading implementations munmap the user stack before
the thread exits resulting in errors due to the unreadable stack.
We now treat any failed load as a if the loaded value was zero and let
the actual syscall deal with the situation.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
.set noreorder
.set nomacro
.set noreorder
.set nomacro
-1: user_lw(t5, 16(t0)) # argument #5 from usp
-4: user_lw(t6, 20(t0)) # argument #6 from usp
-3: user_lw(t7, 24(t0)) # argument #7 from usp
-2: user_lw(t8, 28(t0)) # argument #8 from usp
+load_a4: user_lw(t5, 16(t0)) # argument #5 from usp
+load_a5: user_lw(t6, 20(t0)) # argument #6 from usp
+load_a6: user_lw(t7, 24(t0)) # argument #7 from usp
+load_a7: user_lw(t8, 28(t0)) # argument #8 from usp
+loads_done:
sw t5, 16(sp) # argument #5 to ksp
sw t6, 20(sp) # argument #6 to ksp
sw t5, 16(sp) # argument #5 to ksp
sw t6, 20(sp) # argument #6 to ksp
.set pop
.section __ex_table,"a"
.set pop
.section __ex_table,"a"
- PTR 1b,bad_stack
- PTR 2b,bad_stack
- PTR 3b,bad_stack
- PTR 4b,bad_stack
+ PTR load_a4, bad_stack_a4
+ PTR load_a5, bad_stack_a5
+ PTR load_a6, bad_stack_a6
+ PTR load_a7, bad_stack_a7
.previous
lw t0, TI_FLAGS($28) # syscall tracing enabled?
.previous
lw t0, TI_FLAGS($28) # syscall tracing enabled?
/* ------------------------------------------------------------------------ */
/*
/* ------------------------------------------------------------------------ */
/*
- * The stackpointer for a call with more than 4 arguments is bad.
- * We probably should handle this case a bit more drastic.
+ * Our open-coded access area sanity test for the stack pointer
+ * failed. We probably should handle this case a bit more drastic.
*/
bad_stack:
li v0, EFAULT
*/
bad_stack:
li v0, EFAULT
sw t0, PT_R7(sp)
j o32_syscall_exit
sw t0, PT_R7(sp)
j o32_syscall_exit
+bad_stack_a4:
+ li t5, 0
+ b load_a5
+
+bad_stack_a5:
+ li t6, 0
+ b load_a6
+
+bad_stack_a6:
+ li t7, 0
+ b load_a7
+
+bad_stack_a7:
+ li t8, 0
+ b loads_done
+
/*
* The system call does not exist in this kernel
*/
/*
* The system call does not exist in this kernel
*/
daddu t1, t0, 32
bltz t1, bad_stack
daddu t1, t0, 32
bltz t1, bad_stack
-1: lw a4, 16(t0) # argument #5 from usp
-2: lw a5, 20(t0) # argument #6 from usp
-3: lw a6, 24(t0) # argument #7 from usp
-4: lw a7, 28(t0) # argument #8 from usp (for indirect syscalls)
+load_a4: lw a4, 16(t0) # argument #5 from usp
+load_a5: lw a5, 20(t0) # argument #6 from usp
+load_a6: lw a6, 24(t0) # argument #7 from usp
+load_a7: lw a7, 28(t0) # argument #8 from usp
+loads_done:
- PTR 1b, bad_stack
- PTR 2b, bad_stack
- PTR 3b, bad_stack
- PTR 4b, bad_stack
+ PTR load_a4, bad_stack_a4
+ PTR load_a5, bad_stack_a5
+ PTR load_a6, bad_stack_a6
+ PTR load_a7, bad_stack_a7
.previous
li t1, _TIF_WORK_SYSCALL_ENTRY
.previous
li t1, _TIF_WORK_SYSCALL_ENTRY
sd t0, PT_R7(sp)
j o32_syscall_exit
sd t0, PT_R7(sp)
j o32_syscall_exit
+bad_stack_a4:
+ li a4, 0
+ b load_a5
+
+bad_stack_a5:
+ li a5, 0
+ b load_a6
+
+bad_stack_a6:
+ li a6, 0
+ b load_a7
+
+bad_stack_a7:
+ li a7, 0
+ b loads_done
+
not_o32_scall:
/*
* This is not an o32 compatibility syscall, pass it on
not_o32_scall:
/*
* This is not an o32 compatibility syscall, pass it on